Variable pitch propeller mechanism



Sept. 4, 1934. Ws. HOOVER VARIABLE PITCH PROPELLER MECHANISM 3 Sheets-Sheet 1 Filed Dec. 2, 1931 R. m 2M 2 y w e fit Y fl B 6 U- h M q. H: J. v n vvv U W A L 7 d 0 WW 5 ATTORNEY.

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" S p -.4 1934- w. s. HOOVER I I VARIABLE PITCH PROPELLER MECHANISM Filed Dec. 2-, 1931 a Sheds-Sheet 2 A INVENTOR.

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ATTORNEY.

p 1934- w. s. HOOVER VAR'JIABLE Pmcfi PROPELLER MECHANISM Filed Dec. 2, 1931 s Sheets -Sheet s 11v VENTOR. M B Y m.

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Patented Sept. 4, I934 VARIABLE PITCH gROPELLER MECHANI M Walter 8. Hoover, Girard, Pa., assignor of onehalf to Patrick H. Crow, Application December 2,

Meadvillc, Pa.

1931, Serial No. 578,513

13 Claims. (Cl. 170-163) This invention relates to improvements in variable pitch propellers and it is among the objects thereof to provide control mechanism for varying the propeller pitch to automatically maintain the engine at substantially a predetermined R. P. M.,

irrespective of altitude and flying conditions.

Another object of the invention is the provision of propeller pitch controlling mechanism which shall be responsive to the R. P. M. of the engine for controlling the pitch setting of the propeller blade.

Another object of the invention is the provision of fully automatic control of pitch setting for normal forward speed of the plane coupled with manual control for taking oil and for ground maneuverability and which shall be adapted to produce complete reversal of pitch setting in landing.

Another object of the invention is the provision of a hydraulic mechanism which shall be operative by varying the oil pressure on both sides of a rotary abutment which pressure is developed by the motivating engine on which the hydraulic unit is employed, and which shall be provided with automatic valve control means for varying the pressure on the rotating abutment in response to variations of the engine speed.

Still a further object of the invention is the provision of simple and compact control mechanism which shall be positive and eflicient in its operation and which shall be especially adapted for use in conjunction with certain propeller hub structures and pitch controlling mechanism therefor which are disclosed in my co-pending applications Serial No. 576,063 and No; 578,514

filed November 19, 1931 and December 2, 1931 respectively.

These and other objects of the invention will become more apparent from a consideration of 0 the accompanying drawings constituting'a part hereof in which like reference characters designate like parts and in which:

Figure 1 is a cross-sectional view partially in elevation 01' a propeller hub embodying the principles of this invention;

Figure 2 is a side elevational view of a split annulus in which the blade roots of the propellers are clamped and by means of which their pitch settings are controlled;

Figure 3 is a cross-sectional view of the hub shown in Figure 1 taken along the lines IIL-III Figure 1;

Figure 4 is a rear elevational view of the hydraulic unit or actuating mechanism showing the drive gear assembled thereto;

around 180 of their periphery,

- ments 10 01' the propeller blade roots 11.

the threaded portions 14 of Figure 5 is an end elevation of the rotary abutment orpiston member employed for actuating the pitch controlling gear;

Figures 6 and 7 are end and side elevational views respectively of a control valve housing;

Figure 8 is a cross sectional view of the valve housing shown in Figure 7 taken along the lines VIIIVIII of Figure 7;

Figure 9 is a side elevation of a governor sleeve valve; and,

Figure 10 is a cross-sectional view of the valve housing taken along the lines X-X Figure 7.

With reference to Figures 1 to 5 inclusive of the drawings, the structure therein illustrated comprises a hub casting 1, the rear portion of which is provided with a spline socket 2 adapted to receive the end of the crank shaft 3 of the motivating engine (not shown). The shaft 3 is secured in the splined socket 2 by a tapered wedge ring 4 that is wedged into the expanded end of the socket by a ring nut 5.

A pair of split annuli 6, having gear teeth 7,

as shown in Figure 2, are disposed within the extensions 8 of the hub and are provided with grooves or shoulders 9 which intimately engage anchorage abut- The split annuli are secured by wedge rings'12 which are provided with notches 13 for receiving a spanner wrench by which they are screwed onto the annuli 6. By

their threads, the

turning the wedge rings 12 on relatively thin tapered ends 15 of the blade anchorage members are pressed inwardly, they being provided with slots 16, Figure 2, for this purpose, so that the propeller blades may be securely anchored tp the split annuli 6 to render them rotatable therewith.

Shoulders 1B of the conical flanges 01' the split annuli 6 abut against ball bearing races 19. Similar ball races 20 are provided which abut against the shoulders 22 01' the hub casting and ball bearings 21 are disposed between the races 19 and 20 forming anti-friction thrust bearings against which the thrust 01' the propeller blades reacts.

A beveled gear 23 is mounted on the splined end 24 of a rotary abutment 25, Figure 5, which is disposed in a casing 26. A torson spring 27 having one end connected to the casing 26 and one end to the gear 23 at 28 biases the gear 23 to 110 (iii what may be termed its normal position which is the normal pitch setting of the propeller blades.

The rotary piston 25 and the casing 26 may be termed an hydraulic unit which is assembled on an end bracket 29 which is adapted to be fastened to the propeller hub by means of cap bolts which extend through the openings 30 of the end bracket to have screw thread engagement with the hub casting.

As shown in Figure 5, the rotary piston 25 is provided with abutments and is further provided with ports 32 and 33 which establish communication between the opposite faces of the vanes or blades 31. Similar stationary abutments 31 are provided in the casing 26 which cooperate with the movable abutments of mem-- ber 25.

The spaces between the vanes 31 and the reaction abutments 31' of the outer casing 26, constitute pressure chambers which have ported passages 34 and 35. Figure 3, leading to conduits 36 and 37 respectively, the conduits passing through the hollow engine shaft 3 to a governor valve control system shown in Figures 6 to 10 inclusive of the drawings.

A pair of conduits 38 and 39 communicate at their rear ends with a collector ring 40 into which the scavenged gases of the engine pass and from which they are routedthrough the conduits 38 and 39 to the hollow propeller blades out of which they pass through reaction vents provided for that purpose.

The fluid pressure connections of the conduits 36 3'? are controlled by a governor valve comr prising the following mechanism.

A valve block 42 houses a sleeve valve 43 which is adapted for axial movement in a sleeve 44 secured for adjustment by ring nuts 45.' By adjusting the nuts 45, sleeve 44 is adjusted axially so that th governor expansion may be coordinated with the desired oil pressures. The sleeve 4.4 is provided with triangular shaped ports 46 and 47 respectively communicating with the conduits 36 and 3'1 leading to the fluid chambers of the hydraulic unit disclosed in Figures 1 and 3 of the drawings.

The governor sleeve 43 is actuated in its flow controlling movements by a governor generally designated at 48 consisting of the usual ball levers 49 which are hinged at 50 to a cross-arm 51 of a shaft 513. The arms 48 are connected by links 53 to a collar 54, the shoulder of which engages a groove 55 in the end of the sleeve valve 43 to subject the latter to sliding movement in an axial direction in response to the radial movement of the balls 49.

The ends of the shaft 52 abut against thrust bearings 56 and one end of the shaft is provided with a bevel gear 57 which is cooperatively engaged with a gear 58 of a drive shaft 59 that is operated through an adaptor to run in synchronism with the engine.

As shown in Figure 9, the governor sleeve valve is provided with triangular shaped ports 60B and 61A which cooperate with ports 46 and 4'? of the stationary sleeve 44 and a port 62 is provided which is of elongated form, the length of which corresponds to the axial movement of the valve in response to the governor action, this port communicating with a passage 63 that leads to a hold pressure conduit 64 connected to the pressure pump of the motor.

The sleeve valve 43 is further provided with a slot or opening 65 which is adapted for engagement by a finger 66 formed integrally with a rotatable shaft 67 which, when subjected to angular movement, is adapted to slide the sleeve valve independently of the movement of the governor, this constituting the manual control of the gov-- ernor valve. An assembly plate 68 is fastened to the valve block 42 by cap bolts, Figure 6. V

The lower part of the governor casting is provided with a cavity 70 which encloses the governor drive gears 57 and 58 and which is provided with a plate and gasket for holding the oil which escapes from the oil release valve action of both valves. An oil level is maintained in this cavity by an overflow connection 71 which routes the' oil to the oil pump of the motor and subsequently returns it to the main oil tank.

As shown in Figure 10, the oil cavities which communicate with the conduits designated as 36 and 37 in Figures 6 and 'l of the drawings and the ports 46 and 4'7 of the governor sleeve, have passages 72 and 73 extending through the valve block to the threaded connections of the conduits 36 and 37. A passage '74 connects the passages 72 and '73 with a pressure release passage '75 that extends to the cavity 70 in the bottom of the valve block.

Sleeves '76 are adapted for axial movement in the enlarged portions or the passages 72 and '73 and valves the shape of balls 7'! are disposed in the sleeves '76 and are normally biased by coil springs '78 against their conical seats in the bottom of the sleeve.

These valves function to increase or decrease the oil pressure on the rotary abutments of the propeller blade actuating member in response to the movement of the governor control valve 43. For example, if the position of the ball governor is such as to reduce or entirely close the port of one of the passages 72 or '73, the pressure in the corresponding conduits will be lowered and the ball valve will be permitted to seat. At the same time, the pressure in the other conduit will be increased thereby producing a pressure in the opposite direction in the conduits from which the pressure has been released and cause the fluid to flow through the vent passage'l5. At the same time this pressure will cause the valve 77 to seat and displace the sleeve '76 in a downward. direction to open the passage to the vent '75.

After the governor has changed its position in response to engine speed, the port first closed or partially closed will open and the other port controlled to vary its pressure with the same results, namely, the releasing of the pressure on one side of the abutment and the application of increased pressure on the other side of the rotary abutment to effect a corresponding change in the setting of the pitch of the propeller blades.

The operation of the pitch control mechanism and the hydraulic operating device therefor, is briefly as follows:

The propeller blades, having been mounted in the split annuli 6 with their anchorage abutments in intimate engagement with the annull and with the end rings 12 screwed in place are rotatable in the hub member 1 in response to rotary movement of the actuating bevel gear 23. On account of the torsion spring 21 subjecting gear 23 to angular movement in one direction, the co-acting teeth of the split annuli 6 will bias the propeller blade to the normal advanced setting of the pitch angle, and the blades will retain this position so long as the hydraulic unit is inoperative.

After the engine is cranked, the oil pressure of the engine will be built up in the oil pumping system and communicated by the supply conduit 64 iii pounds, it will be available to actuate the hydraulic unit at all speeds of the engine.

of the normal blades and resulting in increased R. P. M. of the motor. The governor continues to expand until the pitch of the blades permit the motor to revolve at its recommended ground R. P. M., and its speed will thereafter remain substantially constant.

When in taking off the pilot wishes to lessen give his motor more complete'reversal of the blade to obtain ground manueverability with a steerable tail wheel.

Still another use of the manual control develops when the pilot desires to cruise at full throttle after obtaining his cruising altitude to obtain the greatest speed possible. By adjusting the manual control knob clockwise, he will increase the degree of pitch setting thereby reducing to a minimum the piston travel in feet per minute coupled with the highest possible speed resulting in more economical use of fuel.

However, in normal operation, the pilot will release the manual control when the proper cruising altitude has been reached, and the governor valve will immediately respond to automatically control the pitch setting in accordance with the load to maintain a constant or substantially constant engine speed.

As previously herein stated, the automatic function of the governor valve causes the hydraulic fluid such as the oil which is delivered through the conduit 64 to be conducted under pressure through the ports 46 and 47 of the governor valve from which it is conducted through passages 72 and 73 to the conduits 36 and 37 from which it passes to the cavities in the hydraulic unit 25 where it acts on the rotary abutment 31 of the rotary piston member 25.

In passing through the passages 72 and 73, the oil pressurewill displace the balls 77 within the sliding sleeves 76 against the pressure of springs 78 and at the instant the engine cranks, the oil pressure will act substantially equal on both abutments 31 of the rotary piston.

As the engine speed increases, the governor valve will vary the openings of ports 46 and 47 thereby reducing pressure on one abutment and increasing the pressure on the other abutment it W111 be seen thereby decreasing the pitch angle or the propeller blade.

off, the governor will retract and lower the govticular engine speed at which the maximum power and engine efliciency is obtained.

With reference to Figure of the actuating gear 23.

When the plane in flight suddenly drops thereby temporarily decreasing the load on the motor the momentary pull of The engine control as effected mechanically, operated type of pitch setting devices unequalized thrust would be inevitable on ,tri-motor planes.

Also, on multi-motored insulation with outwing mounting the manual control may be omitted from the governor casting assembly on the outwing motors and used only on the center motor for reversal and for ground maneuvering.

Although the hydraulic control mechanism has been described in conjunction with internal combustion engines as the motivating medium, it is apparent that it may be employed for controlling the pitch of the propeller blades in conjunction with any source of motive power such as, for example, steam turbines or electric motors, since its operation is merely dependent upon a connection of an oil pump with the prime mover in any suitable manner.

It is also evident that the governor valve casting 42 may be integrally formed. with the crank case of the motor instead of constituted as an individual unit as herein illustrated, and it will be further evident to those skilled in the art that various other modifications may be made in the details of construction without departing from the principles herein set forth. One of the primary features of the invention is the positive gear tooth connection of the propeller blade structures with the actuating unit to effect positive and instant response to movement effected by the hydraulic control after the motor is cranked and which is equally positive in assuming its advanced setting of pitch angle in response to the normal bias of the torsion spring 2'! if the fluid pressure fails to act on the rotary abutment of the hydraulic actuator.

I claim:

1. A reversible pitch propeller mechanism comprising in combination with a propeller hub, a plurality of propeller blades anchored to said hub to adapt them for angular movement about their respective axes, teeth on said anchorages, an actuating gear having its teeth coacting with the teeth formed in the blade anchorages, a rotary abutment for actuating said gear, a stationary abutment cooperating with said rotary abutment means for normally biasing said gear in the direction of advance setting of pitch angle of the propeller blade, and means'independent of the impelling means for displacing said rotary abutment relative to said stationary abutment to subject the rotary abutment to angular movement whereby said actuating gear rotates to vary the pitch angle.

2. In a reversible pitch propeller mechanism comprising connecting means for simultaneously subjecting a plurality of propeller blades to angular movement about their longitudinal axes, a plurality of angularly movable abutments for actuating said connecting means, a hydraulic unit for directing fluid pressure between said abutments and means responsive to the speed of the motivating engine for varying the fluid displacement between said abutments whereby to vary the pitch angle of said blades.

3. In a variable pitch propeller mechanism comprising in combination a pair of operatively disposed propeller blades, of means for coordinating said blades to effect angular movement thereof around their longitudinal axes, actuating mechanism for said coordinating means comprising a hydraulic unit embodying rotary abutments connected to said pitch coordinating means and responsive to fluid pressure of predetermined force, and means responsive to the speed of the motivating engine for regulating the volume of the fluid on both sides of said rotary abutment whereby to vary the pitch angle of said propeller blades.

4. In a variable pitch propeller mechanism comprising in combination a plurality of propeller blades mounted for angular movement about their longitudinal axes, a pitch coordinating mechanism for subjecting said blades to rotary movement concurrently to vary their pitch angle, an actuating mechanism therefor comprising rotary piston member operated by fluid pressure, means for supplying fluid under pressure to said piston member, and valve means for controlling the flow of fluid to advance or reverse the pitch angle, said valve being controlled in response to the speed of the motivating engine to vary the pitch angle of the blades to maintain a constant load on the motor.

5. In a variable pitch propeller mechanism comprising a plurality of propeller blades disposed in coaxial alinement and mounted for angu lar movement about their longitudinal axes, a pitch coordinating mechanism connecting said blades, actuating mechanism therefor comprising a rotary piston member having rotary abutments, a plurality of conduits for conducting fluid pressure to opposite sides of said abutments to subject the piston to angular-movement in opposite directions, valve means for controlling the flow of fluid to either or both sides of said abutment, said valve means being provided with a governor and a connection with the motor whereby the 'valve is operated in response to the speed of said motor to control the flow of fluid pressure to said rotary abutments to either retard or reverse the angle of pitch setting in accordance with the load acting upon said motor.

6. A variable pitch propeller mechanism comprising a pair of propeller blades mounted for rotary movement with their axes in coaxial alinement, a pitch coordinating gear having tooth engagement with the blade mounting whereby they are concurrently subjected to rotary movement, a hydraulic unit for actuating said gear, and a torsion spring for normally biasing said gears in the direction of advance setting of the propeller pitch angle, a fluid pressure system for said bydraulic unit embodying a governor valve controlling a plurality of ported passages whereby fluid,

is conducted under pressure to the hydraulic unit, and a drive connection coupling said governor valves with the propeller moto' r to apply the fluid pressure to the hydraulic unit for varying the pitch angle in response to the speed of said motor.

7. A variable pitch propeller mechanism comprising a pair of propeller blades mounted for rotary movement with their axes in alinement, a pitch coordinating gear having tooth engagement with the blade mounting whereby the blades are concurrently subjected to rotary movement, means for normally biasing said blades in normal advance setting of pitch angle, and means for actuating said coordinating mechanism to vary the pitch angle, said means comprising a hydraulic unit including a source of fluid under constant pressure, a valve controlling the fluid in its passage to the actuating mechanism, said valve being geared to the motor to be responsive to the speed thereof for varying the pressure to change the pitch angle, and manually operable means for adjusting said valves independently of the speed of the motor to vary the propeller pitch angle.

8. In a variable pitch propeller mechanism comprising a pair of blades mounted for angular movement with their axes in alinement, of a coordinating mechanism having tooth engagement with the blades to concurrently subject them to movement in the setting of their pitch angle, a hydraulic actuating device for said coordinating mechanism including means'for conducting fluid under pressure from a source of supply, a valve controlling the flow of said fluid through multiple passages to said actuating device, a governor for operating said valve in response to the speed of the motivating engine, and manually operable means associated with said valves and operable independently of said governor for controlling the flow of fluid to effect the setting of the pitch angle independently of the engine speed.

9. In a hydraulic unit for changing the setting of the pitch angle of variable pitch'propellers comprising a rotary member embodying angularly movable piston members adapted to be actuated by fluid pressure to rotate in either direction, valve mechanismcontrolling the flow of fluid to change the direction of said actuating member, and a governor for said valve, said governor being operatively connected to a prime mover to control said valve in response to the motivating engine of said propeller, to vary the pitch angle in accordance with the load on the engine to maintain said engine at substantially constant R. P. M.

10. A variable pitch propeller mechanism com prising a plurality of propeller blades anchored for rotary movement in coaxial alinement and having gear teeth provided around the blade anchorages, a coordinating gear wheel having its teeth coacting with the teeth of said blade anchorages, a hydraulic unit for actuating said 00- ordinating gear, and a torsion spring adapted to bias said gear in the direction of normal setting of the pitch angle of said blade independent of the operation of said hydraulic unit.

11. In a variable pitch propeller mechanism comprising in combination a plurality of propeller blades mounted for angular movement about their longitudinal axes, a pitch coordinating mechanism for subjecting said blades to angular movement, concurrently to vary their pitch angle, an actuating mechanism therefor comprising rotary piston member operated by fluid pressure, means for supplying fluid under pressure to said piston member, and valve means operative in responseto variations in the engine speeds for controlling the flow of the fluid to said piston members to advance or reverse the pitch angle.

12. In a variable pitch propeller mechanism comprising in combination, a plurality of propeller blades mounted for angular movement about their longitudinal axes, a pitch coordinating mechanism for subjecting said blades to angular movement concurrently including a common actuator for the blade moving members, the actuator being adapted to move the blades at a reduced ratio to the movement of said actuator, fluid pressure means for actuating the pitch coordinating mechanism, and valve mechanism operative to control the flow of fluid in accordance with the desired angle of pitch setting.

13. In a variable pitch propeller mechanism comprising a propeller hub mounted on an engine shaft, a plurality of propeller blades mounted for angular movement about their longitudinal axes in said hub a pitch coordinating mechanism for subjecting said blades to angular movement concurrently to pressure actuating mechanism therefor operative by the lubricating fluid of the engine, and valve mechanism operative in response the engine speed to control the application of the fluid vto said actuating mechanism.

WALTER S. HOOVER.

vary their pitch angle, a fluidto variations in 

